<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        boby{
            background-color: black;

            margin: 0;
        }
        img{
            position: absolute;
        }
    </style>
</head>
<body>
<script src="jq.js"></script>
<script>
    setInterval(function () {
        let img=$("<img src='rain.png'>");
        let size =parseInt(Math.random()*31)+20;
        img.css("width",size+"px");
        let w=$(window).width();
        let left=parseInt(Math.random()*(w-size));
        img.css("left",left+"px");
        let h=$(window).height();
        img.animate({"top":(h-size)+"px"},size*100).fadeOut(1000,function () {
            img.remove();
        });
        $("body").append(img);
    },10)
</script>
</body>
</html>